War of the microbial world: Acanthamoeba spp. interactions with microorganisms

Abstract

Acanthamoeba is known to interact with a plethora of microorganisms such as bacteria, fungi and viruses. In these interactions, the amoebae can be predatory in nature, transmission vehicle or an incubator. Amoebae consume microorganisms, especially bacteria, as food source to fulfil their nutritional needs by taking up bacteria through phagocytosis and lysing them in phagolysosomes and hence play an eminent role in the regulation of bacterial density in the nature and accountable for eradication of around 60% of the bacterial population in the environment. Acanthamoeba can also act as a “Trojan horse” for microbial transmission in the environment. Additionally, Acanthamoeba may serve as an incubator-like reservoir for microorganisms, including those that are pathogenic to humans, where the microorganisms use amoebae’s defences to resist harsh environment and evade host defences and drugs, whilst growing in numbers inside the amoebae. Furthermore, amoebae can also be used as a “genetic melting pot” where exchange of genes as well as adaptation of microorganisms, leading to higher pathogenicity, may arise. Here, we describe bacteria, fungi and viruses that are known to interact with Acanthamoeba spp.

Exploring the nature of interaction between shiga toxin producing Escherichia coli (STEC) and free-living amoeba - Acanthamoeba sp

“…Whether the astA gene identified in the ECORI strain was derived from another E. coli strain simultaneously present in the Acanthamoeba or acquired in another different way, remains to be ascertained. Whatever the mechanism was, however, our findings suggest that the acquisition of exogenous genes by bacteria during their permanence into Acanthamoeba is possible and strengthen the role of this amoeba as a gene melting pot (Mungroo et al, 2021). In conclusion, our findings showed that E. coli, including STEC, can survive inside protozoan for extended periods of time.…”

“…was evidenced for STEC but also for the non-pathogenic commensal E. coli strain (ECORI). There are no reports describing this condition, however a non-invasive E. coli K-12 strain has been shown to be present intracellularly in amoebas, even if, after a short time it was lysed by amoebas, indicating E. coli K-12 as bacterial prey rather than an endosymbiont (Mungroo et al, 2021). We hypothesize that the strain used in this study, being a commensal in human intestine, may have acquired mechanisms allowing it to resist within the free-living amoebae.…”

Inhibitory and anti-adherent effects of Piper betle L. leaf extract against Acanthamoeba triangularis in co-infection with Staphylococcus aureus and Pseudomonas aeruginosa: A sustainable one-health approach

“…A previous study by Mungroo et al . [ 44 ] demonstrated that the Acanthamoeba -bacteria co-operative relationship improved Acanthamoeba survival.…”

The impact of environmental factors on the transport and survival of pathogens in agricultural soils from karst areas of Yunnan province, China: Laboratory column simulated leaching experiments

“…We speculated that at 20°C, the protozoa thrived, while the bacteria including coliforms were being preyed by the thriving protozoa ( Bott and Kaplan, 1990 ). Most bacteria and some coliforms are digested as a food source, while most coliforms are able to resist lysosomal attack and therefore multiplied within membrane-bound vacuoles ( Barker et al, 1999 ; Van Elsas et al, 2011 ; George et al, 2020 ; Mungroo et al, 2021 ). Previous studies have noted that protozoa, such as Acanthamoeba, can inhibit bacterial growth through the release of free radicals in their lysates ( Connor et al, 1993 ), but have no inhibitory effect on certain coliforms, such as E. coli .…”